|GNU Compiler Collection (GCC) Internals: Data Output|
These hooks specify assembly directives for creating certain kinds
of integer object. The
TARGET_ASM_BYTE_OP directive creates a
byte-sized object, the
TARGET_ASM_ALIGNED_HI_OP one creates an
aligned two-byte object, and so on. Any of the hooks may be
NULL, indicating that no suitable directive is available.
The compiler will print these strings at the start of a new line, followed immediately by the object’s initial value. In most cases, the string should contain a tab, a pseudo-op, and then another tab.
assemble_integer function uses this hook to output an
integer object. x is the object’s value, size is its size
in bytes and aligned_p indicates whether it is aligned. The
function should return
true if it was able to output the
object. If it returns false,
assemble_integer will try to
split the object into smaller parts.
The default implementation of this hook will use the
TARGET_ASM_BYTE_OP family of strings, returning
when the relevant string is
Define this hook if the target assembler requires a special marker to terminate an initialized variable declaration.
A target hook to recognize rtx patterns that
can’t deal with, and output assembly code to file corresponding to
the pattern x. This may be used to allow machine-dependent
UNSPECs to appear within constants.
If target hook fails to recognize a pattern, it must return
so that a standard error message is printed. If it prints an error message
itself, by calling, for example,
output_operand_lossage, it may just
A C statement to output to the stdio stream stream an assembler
instruction to assemble a string constant containing the len
bytes at ptr. ptr will be a C expression of type
char * and len a C expression of type
If the assembler has a
.ascii pseudo-op as found in the
Berkeley Unix assembler, do not define the macro
A C statement to output word n of a function descriptor for
decl. This must be defined if
is defined, and is otherwise unused.
You may define this macro as a C expression. You should define the expression to have a nonzero value if GCC should output the constant pool for a function before the code for the function, or a zero value if GCC should output the constant pool after the function. If you do not define this macro, the usual case, GCC will output the constant pool before the function.
A C statement to output assembler commands to define the start of the constant pool for a function. funname is a string giving the name of the function. Should the return type of the function be required, it can be obtained via fundecl. size is the size, in bytes, of the constant pool that will be written immediately after this call.
If no constant-pool prefix is required, the usual case, this macro need not be defined.
A C statement (with or without semicolon) to output a constant in the constant pool, if it needs special treatment. (This macro need not do anything for RTL expressions that can be output normally.)
The argument file is the standard I/O stream to output the assembler code on. x is the RTL expression for the constant to output, and mode is the machine mode (in case x is a ‘const_int’). align is the required alignment for the value x; you should output an assembler directive to force this much alignment.
The argument labelno is a number to use in an internal label for the address of this pool entry. The definition of this macro is responsible for outputting the label definition at the proper place. Here is how to do this:
(*targetm.asm_out.internal_label)(file, "LC", labelno);
When you output a pool entry specially, you should end with a
goto to the label jumpto. This will prevent the same pool
entry from being output a second time in the usual manner.
You need not define this macro if it would do nothing.
A C statement to output assembler commands to at the end of the constant pool for a function. funname is a string giving the name of the function. Should the return type of the function be required, you can obtain it via fundecl. size is the size, in bytes, of the constant pool that GCC wrote immediately before this call.
If no constant-pool epilogue is required, the usual case, you need not define this macro.
Define this macro as a C expression which is nonzero if C is used as a logical line separator by the assembler. STR points to the position in the string where C was found; this can be used if a line separator uses multiple characters.
If you do not define this macro, the default is that only the character ‘;’ is treated as a logical line separator.
These target hooks are C string constants, describing the syntax in the assembler for grouping arithmetic expressions. If not overridden, they default to normal parentheses, which is correct for most assemblers.
These macros are provided by real.h for writing the definitions
ASM_OUTPUT_DOUBLE and the like:
These translate x, of type
REAL_VALUE_TYPE, to the
target’s floating point representation, and store its bit pattern in
the variable l. For
REAL_VALUE_TO_TARGET_DECIMAL32, this variable should be a
long int. For the others, it should be an array of
long int. The number of elements in this array is determined
by the size of the desired target floating point data type: 32 bits of
it go in each
long int array element. Each array element holds
32 bits of the result, even if
long int is wider than 32 bits
on the host machine.
The array element values are designed so that you can print them out
fprintf in the order they should appear in the target